Abstract: Using a general analytical solution to solve the vibration problem of orthotropic rectangular plates with intermediate support, the general analytical solution can be used to solve the vibration problem of rectangular plates with arbitrary boundary conditions of all edges. The procedure is firstly dividing the plate into two plates along the intermediate line. The deflection is zero; the slope and moment are equal for the connected edges between two plates. The each natural frequency and corresponding vibration mode can be solved by making use of all boundary as well as continuous conditions. Some plates with boundary conditions of simply supported, clamped or free edges have been calculated.